Method for operating a jet propulsion engine with solid fuels



F. J. MAAS 3,303,652

METHOD FOR OPERATING A JET PROPULSION ENGINE WITH SOLID FUELS Feb. 14,1967 Filed Nov. 23, 1964 I IIII IIIIIIIIIIIIIIIIII F/GZ United StatesPatent 3,303,652 METHOD FOR OPERATING A JET PROPULSION ENGINE WITH SOLIDFUELS Friedrich Julius Maas, Zurich, Switzerland, assignor to KemenczkyEstablishment, Vaduz, Liechtenstein, a corporation of LiechtensteinFiled Nov. 23, 1964, Ser. No. 413,159 Claims priority, applicationSwitzerland, Nov. 23, 1963, 14,376/ 63 2 Claims. (Cl. 60204) The presentinvention relates to a jet propulsion engine for watercraft. Jetpropulsion engines of this type are known in different designs anddescribed per example in US. Patent No. 3,060,682 or in the pendingSwiss applications Serial Nos. 6,538/ 63 and 7,337/ 63 assigned to thesame assignee as the present application.

A jet propulsion engine for watercraft of the mentioned type areprovided with a thrust tube being filled up with water through a checkvalve at the tubes entrance. The thrust tube is connected to a pressurechamber by a valve of suitable construction through which successive gasshocks are passed into thrust tube for expelling the column of watertherein and for exercising a corresponding force in opposite directionto the engine. For producing the gas shocks the jet propulsion enginesof the type similar to US. Patent 3,060,682 are using a liquid fuel anda carburator to prepare in a combustion chamber an explosive fuel/ airmixture, which is ignited in successive time intervals. According to theabove mentioned pending Swiss application Serial No. 6,538/ 63 thecarburator may be replaced by a fuel injection equipment. As describedin the above mentioned pending Swiss application Serial No. 7,337/63 thecombustion chamber may be filled up with high pressure steam from aseparate water steam boiler and connected to the thrust tube insuccessive time intervals for producing the desired gas shocks.

The main object of the present invention is to replace the use of liquidfuels as well as the separate steam boiler by a method for operating ajet propulsion engine for watercraft provided with a thrust tube beingfilled with water through a check valve at the entrance and beingconnected to a pressure chamber by a valve means through which insuccessive time intervals gas shocks are passed into the thrust tube forexpelling the water column therefrom. The invention is characterized bygas shocks produced by disintegration of a solid fuel.

These and still further objects of the present invention will becomemore apparent from the following detailed description thereof to be readwith reference to the accompanying drawings in which:

FIG. 1 shows a longitudinal section of an embodiment of a jet propulsionengine operated according to the present invention by solid fuel;

FIG. 2 shows another embodiment of a jet propulsion engine forwatercraft suitable to be operated by solid fuel according to thepresent invention.

The jet propulsion engine shown in FIG. 1 is provided with a pressurechamber 17 and valve means for intermittent connection to the thrusttube 100 similar to the corresponding parts described in the pendingSwiss application Serial No. 7,337/ 63. During operation of the enginethe thrust tube is below the water level 11 and provided with a checkvalve per example consisting of the blades 12 radially extending from aspindle-shaped rotation shaft 13. By this check valve 12, 13 theentrance of the thrust tube 10 is open for a water stream only in thedirection 14 but closed for the outlet of the water column from thethrust tube 10 in opposite direction.

The thrust tube 10 is connected to the pressure chamber 17 through acircular opening 15 which is closed against gas or water flow by adisk-shaped valve head 16. The pressure chamber 17 and the valve head 16together with its mechanism are a common structure arranged in the .heatinsulated inner space 20 of a streamline shaped support 19 for thethrust tube 10. The upper part of the support 19 is provided with achamber 70 for accumulating high pressure gas.

The high pressure gas used for operating the jet propulsion engine issupplied from the gas chamber 70 through the connection 22 into thepressure chamber 17. The orifice of the connection 22 is arranged in thepressure chamber 17 above the cone shaped valve seat 23 constitutingtogether with the cone shaped ring 24 at the stem 25 an inlet valve forthe high pressure gas stream. This inlet valve 23, 24 is closing the gassupply from the connection 22 to the pressure chamber 17 after havinglifted the stem 25 high enough to press the ring 24 to the valve seat23.

The position of rest of the valve head 16 carried by the stem 25 isshown in FIG. 1 and in this position the connection between the pressurechamber 17 and the thrust tube 10 is closed. Accordingly the inlet valve23, 24 is opened and high pressure gas is 'fiowing from the connection22 into the pressure chamber 17. Through a conduit 26, the needle valve27 and a bore 28 the pressure chamber 17 is connected to a controlchamber 29 being closed at the top with a piston plate 30 carried by thestem 25. In the rest position the needle valve 27 is closed and theconnection between the conduit 26 and the bore 28 is interrupted. Onlywhen the gas in the pressure chamber 17 comes up to a predeterminedvalue the needle valve 27 is opening the connection from the pressurechamber 17 through the conduit 26 and the bore 28 to the control chamber29 which acquires the same gas pressure. Because the area of the pistonplate 30 exposed to the control chamber 30 is larger than the area ofthe valve head 16 the upward force against the piston plate 30 and thestem 25 is overbalancing the downward force on the stem 25 carried outby the valve head 16. Accordingly the stern 25 is moved upward by thepiston plate 30 and the valve head 16 is lifted opening the connectionbetween the pressure chamber 17 and the thrust tube 10.

The upward motion of the stem 25 is finished as soon as the cone shapedvalve ring 24 is pressed against the valve seat 23 closing the inletvalve for the gas supply connection 22. Before the stem 25 reaches thisupper end position the pressure in the pressure chamber 17 is decreasedfar enough that the needle valve 27 is again closed interrupting theconnection between the pressure chamber 17 and the control chamber 29.In the upper end position of the stem 25 the curved rear surface 31 ofthe valve head 16 is contacting the edge 32 in the pressure chamber 17closing the upper part of the pressure chamber 17 as well as the inletvalve 23, 24 and the orifice of the conduit 26 against the lower part ofthe pressure chamber 17. Furthermore in this upper end position of thestem 25 the outlet valve 33 arranged below the piston plate 30 is liftedfrom its seat and hence the control chamber 29 is connected through theconduit 35 to the lower part of the pressure chamber 17.

At the moment the valve head 16 is lifted by the stem 25 a gas shock isdirected through the opening 10 upon the water column in the thrust tube10 from the high pressure gas filling of the lower part of the pressurechamber 17. The gas from the lower part of the pressure chamber 17 aswell as from the control chamber 29 is flowing through the opening 15into the thrust tube 10.

After the expellation of the water column from the thrust tube 10 isfinished, the gas pressure in the lower part of the pressure chamber 17becomes lower than in its upper part which is closed by the rear of thevalve head 16 contacting the edge 32 so that a downward force is arisingupon the valve head 16 and the stem 25. This force is increased by thepressure of the gas in the connection 22 upon the valve ring 24. As aresult of these forces increased by the own weight of all the partscarried by the stem 25 the valve head 16 is falling down and closingagain the opening 15 between the pressure chamber 17 and the thrust tubefurthermore the outlet valve 33, 34 of the control chamber 29 is closedand the high pressure gas is flowing from the connection 22 through theopen inlet valve 23, 24 into the pressure chamber 17. Now the mechanismis again in the position of rest shown in FIG. 1.

By the above described action of the valve mechanism successive gasshocks are passing the opening and exercised to the water column in thethrust tube 10. The valve mechanism is a self interrupting push-pullvalve at the connection 22 supplying the high pressure gas into thepressure chamber 17 and at the opening 15 between the pressure chamber17 and the thrust tube 10. Besides the dimensions of the mechanism theadjusting of the needle valve 27 is responsible for the operationfrequency of the self interrupting push-pull valve; hence the frequencyis continuously variable within a broad range. An embodiment of asuitable needle valve 27 is described in detail in the above mentionedSwiss application Serial No. 7,337/63; the highest operation frequencyis 40 to 50 cycles per second and lower frequencies are adjustable. I

The valve mechanism described above in connection with FIG. 1 is apreferred embodiment of a mechanical self-interrupting push-pull valvehaving an operating frequency adjustable by the response pressure of theneedle valve 27. Nevertheless other embodiments of valve mechanism aresuitable; per example the pressure responsible needle valve 27 may bereplaced by a control means not pressure responsible but arranged toconnect the conduit 26 and the bore 28 from the pressure chamber 17 tothe control chamber 29 at predetermined time intervals. Such a controlmeans may be responsible, per example, to the pressure pulses arising inthe thrust tube 10 during the water column is expelled therefrom. Alsoan external controlled valve means may be used, per example a magnetcontrolled valve which is operated by electric control pulses with afrequency adjusted according to the desired operating frequency of thevalve mechanism. Moreover in a mechanism comprising the valve head 16and the gas inlet valve 23, 24 the control chamber 29 may be avoided andreplaced by suitable spring means. Also a magnetic operation of thevalve head 16 and the gas inlet valve 23, 24, may be used and theoperating frequency adjusted by exciting the magnet coils by suitableelectric current pulses.

The high pressure gas necessary for the operation of the jet propulsionengine shown in FIG. 1 is supplied to the gas chamber 70 through theconnection 71 from a gas generator 72 for solid fuels. The gas generator72 comprises, per example a case containing gun powder in the form ofpressed rods 73. Similar high pressure gas generators suitable for solidfuels are well known in different types as rocket drives. After havingignited the solid fuel, per example by an electrically heated filament(not shown), the suitable prepared gun powder rods 73 are burning withconstant speed without an explosion. The burning process of the rods 73is producing a large gas amount and high pressure and the gas issupplied through a sieve plate 74 and the connection 71 into the gaschamber 70. Normally the burning process cannot be stopped after theignition. The amount and pressure of the produced gas may be influencedby the shape and arrangement of the solid fuel in the generator 72 andthe duration of the burning process is determined by the fuel amountcontained in the case.

The embodiment of the jet propulsion engine shown in FIG. 1 comprises ahigh pressure gas generator using solid fuels; hence it is suitable onlyfor purposes in which the propulsion force is desired only during apredetermined time interval. Per example, a jet propulsion engine ofthis type is suitable for water torpedos or similar purposes. Afterhaving burned down the solidfuel contained in the generator 72, the jetpropulsion engine may be used again after having replaced at the gasgenerator 72 the empty fuel case by a fresh one.

Whilst the embodiment of the jet propulsion engine according to FIG. 1is provided with a gas generator for continuously burning solid fuels asecond embodiment shown in FIG. 2 uses granulated solid fuel and anexplosion of predetermined quantities during successive time intervals.This second embodiment is described in detail below but is shown in FIG.2 only diagrammatically and all less important parts are avoided.

The jet propulsion engine according to FIG. 2 is provided with a thrusttube having a rotating check valve 81 at the entrance of the typedescribed above. The pressure 82 is connected to the thrust tube 80through a valve means 83, preferably provided with a number of flat andpane like lamellae being arranged at small distances parallel one toanother securing only a very small resistance against a gas flow fromthe pressure chamber 82 into the thrust tube 80 but at the same timepreventsany passing of water from the thrust tube 80 into the pressurechamber 82. Additional to this valve means 83 the pressure chamber 82 isprovided with a check valve, per example comprising a perforated plate84 and a number of fiat spring plates 85 closing the openings in theplate 84 when in the position of rest shown in FIG. 2.

The pressure chamber 82 is also provided with several radial extendingribs forming a grill 86 carrying a tray suitable as a receptacle of oneor more particles 87 of the granulated solid fuel. The grill 86 is alsothe support of a feeding 88 being connected to the storage case 90through a dosage means 89 for the granulated solid fuel contained in thecase 90. An insulating body 91 attached to the grill 86 is carrying aspark plug which is connected through an insulated lead in 92 to anelectric current supply 93 outside of the pressure chamber 82.

In adjustable successive time intervals the receptacle of the grill 86is supplied by the dosage means 89 and through the feeding 88 with oneor more particles 87 of the granulated solid fuel from the storage case90. The dosage means 89 and the feeding 88 may be operatedpneumatically, per example. The fuel particles 87 are ignited by anelectric spark and exploded. The pressure shock produced by thisexplosion passes the check valve 84, 85 and the valve means 83 and isexpelling the water column in the thrust tube 80 through the outlet.During the refilling of the thrust tube 80 through the entrance checkvalve 81 the check valve 84, 85 is again closed and from the dosagemeans 89 a quantity of granulated solid fuel is fed into the empty trayon the grill 86 followed by the next ignition and explosion. The dosagemeans 89 is designed in a manner to keep off the pressure shocksproduced by each explosion in the pressure chamber 82 from the storagecase 90 and the solid fuel therein.

As solid fuels are all explosive materials suitable, which can beprepared in granulated form, per example as smalli balls or particles ofother shapes. Per example the:

normal gun powder can be used after being mixed with:

a suitable oxygen carrying material and then granulated.

Also other solid fuels are suitable in granulated form, per

example nitrocellulose and other explosive substances. The Weight of thesingle particles or of the amount of particles fed into the tray foreach explosion cycle are adjusted to produce a pressure shock by eachexplosion which is just sufficient to expell the water column in thethrust tube 80 therefrom.

The above described and in FIGS. 1 and 2 diagramfor other types of jetpropulsion engines for watercraft provided with a thrust tube beingconnected to a pressure chamber by a valve means through which insuccessive time intervals gas or pressure shocks are passed into thethrust tube for expelling the water column therefrom. The gas orpressure shocks are produced by disintegrating a solid fuel. The fuelmay be burned continuously to produce a gas of high pressure which ispassed in successive intervals into the thrust tube. Also granulatedsolid fuel may be used to be exploded in predetermined quantities and insuccessive intervals to exercise pressure or gas shocks to the watercolumn in the thrust tube.

What I claim is:

1. A method of operating a hydrojet engine having a thrust tube forreceiving and expelling water, a check valve positioned in the forwardend of said tube, a pressure chamber in valved, fluid communication withsaid tube downstream of said check valve and a gas producer in valved,fluid communication with said pressure chamber; comprising the steps of(1) continuously burning solid fuel in said gas producer to obtain ahigh pressure gas (2) intermittently supplying said high pressure gas tosaid pressure chamber and (3) intermittently passing said gas from saidchamber to the thrust tube for expelling a column of water therefrom.

2. The method according to claim 1 further com-prising the step ofproviding a gas accumulator between said gas producer and said pressurechamber.

References Cited by the Examiner UNITED STATES PATENTS 730,042 6/1903Okun 1l513 1,838,984 12/1931 Berkowitz 6035.6 2,463,820 3/1949 Staffordet al. (SO-35.6 2,903,850 9/1959 Lang 6035.6 3,157,992 11/1964 Kemenczky60-3977 CARLTON R. CROYLE, Primary Examiner.

1. A METHOD OF OPERATING A HYDROJET ENGINE HAVING A THRUST TUBE FOR RECEIVING AND EXPELLING WATER, A CHECK VALVE POSITIONED IN THE FORWARD END OF SAID TUBE, A PRESSURE CHAMBER IN VALVED, FLUID COMMUNICATION WITH SAID TUBE DOWNSTREAM OF SAID CHECK VALVE AND A GAS PRODUCER IN VALVED, FLUID COMMUNICATION WITH SAID PRESSURE CHAMBER; COMPRISING THE STEPS OF (1) CONTINUOUSLY BURNING SOLID FUEL IN SAID GAS PRODUCER TO OBTAIN A HIGH PRESSURE GAS (2) INTERMITTENTLY SUPPLYING SAID HIGH PRESSURE GAS TO SAID PRESSURE CHAMBER AND (3) INTERMITTENTLY PASSING SAID GAS FROM SAID CHAMBER TO THE THRUST TUBE FOR EXPELLING A COLUMN OF WATER THEREFROM. 